U.S. patent application number 16/826358 was filed with the patent office on 2020-07-09 for laminated glass.
This patent application is currently assigned to AGC Inc.. The applicant listed for this patent is AGC Inc.. Invention is credited to Tokihiko AOKI, Shunsuke SADAKANE.
Application Number | 20200215798 16/826358 |
Document ID | / |
Family ID | 66173672 |
Filed Date | 2020-07-09 |
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United States Patent
Application |
20200215798 |
Kind Code |
A1 |
AOKI; Tokihiko ; et
al. |
July 9, 2020 |
LAMINATED GLASS
Abstract
A laminated glass having an interlayer between a glass plate on
an exterior side of a vehicle and a glass plate on an interior side
of the vehicle, includes a heat generator on a principal surface on
a vehicle-exterior side of the glass plate that is on the interior
side of the vehicle, wherein at least one of the glass plate on the
exterior side of the vehicle and the glass plate on the interior
side of the vehicle has a wedge shape in cross section, and wherein
a maximum value of a layer thickness of the interlayer is less than
or equal to 1 mm.
Inventors: |
AOKI; Tokihiko; (Tokyo,
JP) ; SADAKANE; Shunsuke; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AGC Inc. |
Chiyoda-ku |
|
JP |
|
|
Assignee: |
AGC Inc.
Chiyoda-ku
JP
|
Family ID: |
66173672 |
Appl. No.: |
16/826358 |
Filed: |
March 23, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP2018/038149 |
Oct 12, 2018 |
|
|
|
16826358 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B 27/30 20130101;
B32B 7/027 20190101; B32B 2305/345 20130101; B32B 17/10761
20130101; B32B 2307/102 20130101; B32B 27/06 20130101; B60J 1/00
20130101; B32B 17/10385 20130101; B32B 2329/06 20130101; B32B
2457/00 20130101; B32B 2605/08 20130101; H05B 3/86 20130101; B32B
2307/304 20130101; B32B 2315/08 20130101; B32B 2605/006 20130101;
B60J 1/02 20130101; B32B 17/10036 20130101; B32B 17/10 20130101;
B60S 1/02 20130101 |
International
Class: |
B32B 17/10 20060101
B32B017/10; B32B 27/30 20060101 B32B027/30; H05B 3/86 20060101
H05B003/86 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 20, 2017 |
JP |
2017-203911 |
Claims
1. A laminated glass having an interlayer between a glass plate on
an exterior side of a vehicle and a glass plate on an interior side
of the vehicle, comprising: a heat generator on a principal surface
on a vehicle-exterior side of the glass plate that is on the
interior side of the vehicle, wherein at least one of the glass
plate on the exterior side of the vehicle and the glass plate on
the interior side of the vehicle has a wedge shape in cross
section, and wherein a maximum value of a layer thickness of the
interlayer is less than or equal to 1 mm.
2. The laminated glass as claimed in claim 1, wherein a wedge angle
of a cross section of a glass plate having the wedge shape in cross
section is greater than or equal to 0.2 mrad and less than or equal
to 1.0 mrad.
3. The laminated glass as claimed in claim 1, wherein the glass
plate on the exterior side of the vehicle is a glass plate having
the wedge shape in cross section.
4. The laminated glass as claimed in claim 1, wherein the glass
plate on the interior side of the vehicle is a glass plate having
the wedge shape in cross section.
5. The laminated glass as claimed in claim 1, wherein a thermal
conductivity of the interlayer is less than or equal to 0.3
W/mK.
6. The laminated glass as claimed in claim 1, wherein the
interlayer is formed of a resin selected from among polyvinyl
acetal resin and vinyl acetate copolymer resin.
7. The laminated glass as claimed in claim 1, wherein the
interlayer is a sound insulation performance improving film having
three or more layers.
8. The laminated glass as claimed in claim 1, wherein a heat
generation amount per unit area of the heat generator is greater
than or equal to 400 W/m.sup.2 and less than or equal to 1200
W/m.sup.2.
9. The laminated glass as claimed in claim 1, wherein a ratio of a
plate thickness of a glass plate having the wedge shape in cross
section to a layer thickness of the interlayer at a corresponding
position (the plate thickness of the glass plate/the layer
thickness of the interlayer) is greater than or equal to 0.7 and
less than or equal to 5.0.
10. The laminated glass as claimed in claim 1, wherein a wedge
angle of a cross section of a glass plate having the wedge shape in
cross section is formed such that a wedge angle of a part on an
upper side of the glass plate is smaller than a wedge angle of
another part on a lower side of the glass plate, wherein the part
is above a center of a line connecting a midpoint of the upper side
and a midpoint of the lower side, and said another part is below
the center.
11. The laminated glass as claimed in claim 1, further comprising:
an information transmission/reception area in an upper-side
peripheral part of the laminated glass.
12. The laminated glass as claimed in claim 11, wherein a device
used for information transmission/reception is a camera.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This U.S. non-provisional application is a continuation
application of, and claims the benefit of priority under 35 U.S.C.
.sctn. 365(c) from, PCT International Application PCT/JP2018/038149
filed on Oct. 12, 2018, which is designated the U.S., and is based
upon and claims the benefit of priority of Japanese Patent
Application No. 2017-203911 filed on Oct. 20, 2017, the entire
contents both of which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to laminated glass.
BACKGROUND ART
[0003] In recent years, introduction of head-up displays (also
referred to as "HUD", below) has made progress, with which
predetermined information is displayed in the field of vision of
the driver of a vehicle, by reflecting images on the windshield of
the vehicle. However, there may be cases where double images
(transmitted double images and reflected double images) pose a
problem when the driver is visually recognizing an outside scene or
information displayed by the HUD.
[0004] Thereupon, in the HUD, in order to solve the problem of
double images, technologies to make the cross section of a
windshield wedge-shaped have been adopted. For example, a laminated
glass compatible with HUD has been proposed, in which an interlayer
having a wedge shape in cross section is sandwiched between two
glass plates, to have a wedge shape as a whole (see, for example,
Japanese Unexamined Patent Application Publication No.
H07-175007).
[0005] Meanwhile, in order to clear off snow, ice, frost, and the
like stuck on the exterior surface of a windshield so as to keep
the visibility of the windshield, a laminated glass having an
electrical heating function has been known (see, for example,
Japanese Unexamined Patent Application Publication No.
H09-207718).
[0006] In a laminated glass having such a heating function, a heat
generator including hot wires or a film is installed on the
principal surface on the vehicle-exterior side of the glass plate
that is on the interior side of the vehicle. The heating function
is also required for an HUD-compatible laminated glass described
above.
[0007] However, in the HUD-compatible laminated glass described
above, an interlayer having a wedge shape in cross section is used;
therefore, in the upper part of the laminated glass, namely, a part
where the layer thickness of the interlayer is greater, heat from
the heat generator does not reach easily to the glass plate on the
exterior side of the vehicle; therefore, there is a likelihood that
snow, ice, frost and the like may not be sufficiently cleared
off.
SUMMARY
[0008] According to an embodiment, a laminated glass having an
interlayer between a glass plate on an exterior side of a vehicle
and a glass plate on an interior side of the vehicle, includes a
heat generator on a principal surface on a vehicle-exterior side of
the glass plate that is on the interior side of the vehicle,
wherein at least one of the glass plate on the exterior side of the
vehicle and the glass plate on the interior side of the vehicle has
a wedge shape in cross section, and wherein a maximum value of a
layer thickness of the interlayer is less than or equal to 1
mm.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIGS. 1A-1B are diagrams illustrating a windshield for a
vehicle.
[0010] FIG. 2 is a first partial cross-sectional view of the
windshield 20 illustrated in FIG. 1 sectioned in the XZ direction
and viewed in the Y direction;
[0011] FIG. 3 is a partial cross-sectional view illustrating a
windshield according to a comparative example.
[0012] FIG. 4 is a second partial cross-sectional view of the
windshield 20 illustrated in FIG. 1 sectioned in the XZ direction
and viewed in the Y direction;
[0013] FIG. 5 is a first diagram illustrating examples and a
comparative example; and
[0014] FIG. 6 is a second diagram illustrating examples and a
comparative example.
EMBODIMENTS OF THE INVENTION
[0015] In the following, embodiments will be described with
reference to the drawings.
[0016] According to the disclosed technology, it is possible to
efficiently transmit heat from a heat generator to the glass plate
on the exterior side of the vehicle in a laminated glass that has a
wedge shape in cross section, and is HUD-compatible.
[0017] Throughout the drawings, the same elements are assigned the
same reference symbols, and duplicated description may be omitted.
Note that although a windshield for vehicles will be taken as an
example for the description here, the application is not limited as
such; a laminated glass according to the embodiments can be applied
to glasses other than a windshield for vehicles. Also, in some of
the drawings, the size and shape may be partially exaggerated to
facilitate understanding of the contents of the present
invention.
[0018] FIGS. 1A-1B are diagrams exemplifying a windshield for a
vehicle, which are diagrams schematically illustrating a state in
which the windshield is visually recognized from the vehicle
interior to the vehicle exterior.
[0019] As illustrated in FIG. 1A, the windshield 20 has an HUD
display area R.sub.1 used by an HUD and an HUD non-display area
R.sub.2 not used by the HUD. The HUD display area R.sub.1 covers a
range, in the case where viewed from a point V1 of JIS R3212, on
which the windshield 20 is irradiated with light from a mirror that
constitutes the HUD, when the mirror is rotated. Note that in the
present specification, the transparent area includes a test area C
specified in JIS R3212, and an information transmission/reception
area in the case where the information transmission/reception area
described below is included, and indicates an area where the
visible light transmittance Tv is greater than or equal to 70%.
[0020] The HUD display area R.sub.1 is located in the lower half of
the windshield 20, and the HUD non-display area R.sub.2 is adjacent
to the HUD display area R.sub.1, and located around the HUD display
area R.sub.1 of the windshield 20. However, the HUD display area
may be arranged in multiple locations in the Y direction, for
example, like an HUD display area R.sub.11 and an HUD display area
R.sub.12 illustrated in FIG. 1B. Alternatively, the HUD display
area may be only one of the HUD display area R.sub.11 and the HUD
display area R.sub.12. Alternatively, the HUD display area may be
arranged in multiple locations in the Z direction (not
illustrated).
[0021] It is favorable to arrange the HUD display areas R.sub.1,
R.sub.11, and R.sub.12 outside the test area A specified in JIS
R3212. The HUD display areas R.sub.1, R.sub.11, and R.sub.12 may be
arranged in the test area A specified in JIS R3212. Note that the
test area A is provided inside the test area B, although not
illustrated in FIGS. 1A-1B. In FIGS. 1A-1B, B and C indicate test
areas B and C specified in JIS R3212, respectively.
[0022] It is favorable that a black ceramic layer 29 (shielding
layer) is present in the peripheral part of the windshield 20. The
black ceramic layer 29 may be formed by applying black ceramic
printing ink to a glass surface to be stained. The presence of the
opaque black ceramic layer 29 in the peripheral part of the
windshield 20 enables to prevent an adhesive such as urethane for
holding the peripheral part of the windshield 20 from being
deteriorated by ultraviolet rays.
[0023] In the case where only the interlayer of the windshield 20
has a wedge angle as in the conventional techniques, in a part
where the layer thickness of the interlayer becomes greater, an
ultraviolet absorber in the interlayer has a greater effect of
controlling deterioration due to ultraviolet rays. In the case
where the glass plate has a wedge angle as in the present
invention, the maximum value of the layer thickness of the
interlayer becomes smaller; therefore, it is favorable to have a
black ceramic layer in the peripheral part of the windshield 20.
Also, in the present invention, by having a black ceramic layer in
the peripheral part of the windshield 20, heat from the heat
generator can be easily transmitted to the outer surface side of
the vehicle.
[0024] The windshield 20 may have an information
transmission/reception area R.sub.5 in an upper-side peripheral
part. The information transmission/reception area R.sub.5 may be
arranged, for example, at an opening formed in the black ceramic
layer 29. The information transmission/reception area R.sub.5
functions as a transparent area in the case where a camera, a laser
for distance measurement, and the like are arranged on the
upper-side peripheral part of the windshield 20.
[0025] FIG. 2 is a partial cross-sectional view of the windshield
20 illustrated in FIG. 1 sectioned in the XZ direction and viewed
in the Y direction. As illustrated in FIG. 2, the windshield 20 is
a laminated glass for vehicles provided with a glass plate 210 as
the glass plate on the interior side of the vehicle; a glass plate
220 as the glass plate on the exterior side of the vehicle; and an
interlayer 230. In the windshield 20, the glass plate 210 and the
glass plate 220 are fixed in a state of having the interlayer 230
sandwiched in-between.
[0026] A heat generator 250 is provided on the principal surface on
the exterior side of the vehicle of the glass plate 210. Providing
the heat generator 250 enables to defrost (thaw) frozen water stuck
on the outer surface 22 of the windshield 20, and to clear off
(defog) cloudiness of the outer surface 22 of the windshield 20.
The heat generator 250 is not limited in particular; for example, a
so-called heat wire type in which metal wires such as tungsten
wires are arranged, a so-called coating type in which a transparent
conductive film is formed on the glass through which a current
flows to generate heat, a so-called film type in which conductive
wiring has, for example, a mesh shape, in a base material, and the
like may be listed.
[0027] In the windshield 20, the inner surface 21 of the windshield
20 as one of the surfaces of the glass plate 210 on the interior
side of the vehicle, and the outer surface 22 of the windshield 20
as one of the surfaces of the glass plate 220 on the exterior side
of the vehicle may be flat surfaces, or may be curved surfaces.
[0028] The windshield 20 is formed to have a wedge shape in cross
section such that the thickness increases as it extends from the
lower end side to the upper end side of the windshield 20 when the
windshield 20 is mounted on the vehicle, where 5 represents the
wedge angle. Note that the wedge angle .delta. is defined as a
value obtained by dividing the difference between the thickness at
the lower end and the thickness at the upper end in the vertical
direction along the windshield 20, by the distance in the vertical
direction along the windshield 20 (i.e., a mean of the wedge
angle). In the following, the wedge angles of a glass plate and an
interlayer are similarly defined as above. Note that the increase
in thickness from the lower end side to the upper end side of the
windshield 20 may be a monotonic increase in which the increasing
rate is constant or the increasing rate may vary partially.
[0029] The wedge angle .delta. of the windshield 20 as a laminated
glass is favorably greater than or equal to 0.2 mrad and less than
or equal to 1.0 mrad; more favorably greater than or equal to 0.3
mrad and less than or equal to 1.0 mrad; even more favorably
greater than or equal to 0.3 mrad and less than or equal to 0.9
mrad; and particularly favorably greater than or equal to 0.3 mrad
and less than or equal to 0.8 mrad. Having the wedge angle .delta.
greater than or equal to the lower limit enables to sufficiently
reduce transmitted double images while controlling the HUD double
images. Also, having the wedge angle .delta. less than or equal to
the upper limit enables to control the increase in the mass of the
windshield 20 within a range within which no problem would occur,
and not to hinder the heat from the heat generator 250 from being
transmitted to the outside of the vehicle.
[0030] In the windshield 20, the glass plate 220 is formed to have
a wedge shape in cross section, and the thicknesses of the glass
plate 210 and the interlayer 230 are uniform, respectively. In the
glass plate 220, an angle formed between the surface serving as the
outer surface 22 of the windshield 20 and the surface contacting
the interlayer 230 is the wedge angle .delta.g.
[0031] The wedge angle .delta.g of a glass plate having a wedge
shape in cross section (in FIG. 2, the glass plate 220) is
favorably greater than or equal to 0.2 mrad and less than or equal
to 1.0 mrad; more favorably greater than or equal to 0.3 mrad and
less than or equal to 1.0 mrad; even more favorably greater than or
equal to 0.3 mrad and less than or equal to 0.9 mrad; and
particularly favorably greater than or equal to 0.3 mrad and less
than or equal to 0.8 mrad. Having the wedge angle .delta.g to be
greater than or equal to the lower limit enables to sufficiently
reduce transmitted double images while controlling the HUD double
images. Also, having the wedge angle .delta.g to be less than or
equal to the upper limit enables not to hinder the heat from the
heat generator 250 from being transmitted to the outside of the
vehicle around the upper end of the windshield 20, and to control
the increase in mass of the windshield 20 within a range within
which no problem would occur.
[0032] In the case where both the glass plate and the interlayer
230 have a wedge shape in cross sections, the sum of the wedge
angle .delta.g of the glass plate and the wedge angle of the
interlayer 230 may be adjusted so as to be within an appropriate
range of the wedge angle .delta. of the windshield 20.
[0033] In FIG. 2, the thicknesses of the glass plate 210 and the
interlayer 230 are uniform, respectively; therefore, the wedge
angle .delta.g of the glass plate 220 is equal to the wedge angle
.delta. formed by the inner surface 21 and the outer surface 22 of
the windshield 20 (the wedge angle of the entire laminated glass).
In the example in FIG. 2, although only the glass plate 220 has a
wedge shape in cross section, both the glass plate 210 and the
glass plate 220 may have wedge shapes in cross section (the layer
thickness of the interlayer 230 is uniform).
[0034] In the case where both of the glass plates 220 and 210 have
wedge shapes in cross sections, the wedge angles of the glass
plates may be different or may be the same. In either case of one
of the glass plates 210 and 220 being a glass having a wedge shape
in cross section or both being glasses having wedge shapes in cross
section, it is favorable that the wedge angle of the cross section
of a glass plate having a wedge shape in cross section is formed
such that a wedge angle of a part on the upper side of the glass
plate is smaller than a wedge angle of the other part on the lower
side, where the part is above the center of a line connecting the
midpoint of the upper side and the midpoint of the lower side, and
the other part is below the center. The wedge shape in cross
section described above prevents too thick a plate thickness of the
glass plate close to the upper side, which is unrelated to the HUD
display area of the windshield 20; therefore, it does not hinder
the heat from the heat generator 250 from being transmitted to the
outside of the vehicle.
[0035] Note that although it is favorable that the layer thickness
of the interlayer 230 is uniform (i.e., the wedge angle of 0 mrad),
a slight wedge angle may be generated due to stretching or the like
in the manufacturing process of the laminated glass. In this case,
if the wedge angle of the interlayer 230 is less than or equal to
0.2 mrad, a part of the interlayer 230 where the layer thickness is
greater does not become too thick, and the influence on the thermal
conduction from the heat generator 250 is small; therefore, the
wedge angle falls within the allowable range. In other words, the
wedge angle of the interlayer 230 is favorably less than or equal
to 0.2 mrad, more favorably less than or equal to 0.15 mrad, and
even more favorably 0.1 mrad.
[0036] In the case of forming one or both of the glass plate 210
and the glass plate 220 to have a wedge shape(s) in cross section,
if the glass plate is to be formed of inorganic glass and
manufactured by a float process, the shape can be obtained by
engineering the manufacturing conditions. In other words, by
adjusting the revolving speed of multiple rolls arranged on both
edges in the width direction of a glass ribbon that travels on
molten metal, glass can be formed to have a concave, convex, or
tapered cross section in the width direction, which may be cut to
obtain a part having a desired thickness change. Also, the surface
of the glass plate may be polished so as to be adjusted to a
desired wedge angle.
[0037] As the glass plates 210 and 220, for example, inorganic
glass such as soda-lime glass, aluminosilicate glass, or
alkali-free glass; organic glass; or the like can be used. The
glass plate 220 located on the exterior side of the windshield 20
is favorably made of inorganic glass from the viewpoint of scratch
resistance, and is favorably soda-lime glass from the viewpoint of
moldability. It is favorable that the glass plate having a wedge
shape in cross section contains iron as an oxide by an amount of
greater than or equal to 0.4 mass% and less than or equal to 0.6
mass%. Containing iron among the components makes bending by
heating easier thanks to greater heat absorption, even in the case
where the plate thickness is thick as in the case of a glass plate
having a wedge shape in cross section. Containing iron among the
components also reduces the visible light transmittance, makes the
heat generator 250 less visible, and thereby, makes the design
better.
[0038] The plate thickness of the thinnest part of the glass plate
220 located on the exterior side of the windshield 20 is favorably
greater than or equal to 1.8 mm and less than or equal to 3 mm. The
plate thickness of the glass plate 220 being greater than or equal
to 1.8 mm provides a sufficient strength in terms of stone-chip
resistance and the like, and the plate thickness being less than or
equal to 3 mm prevents the mass of the laminated glass from
becoming too heavy, which is favorable in terms of the fuel
efficiency of the vehicle. Further, heat from the heat generator
250 is transmitted to the outer surface 22 more easily. The plate
thickness of the thinnest part of the glass plate 220 is more
favorably greater than or equal to 1.8 mm and less than or equal to
2.8 mm, even more favorably greater than or equal to 1.8 mm and
less than or equal to 2.6 mm.
[0039] The plate thickness of the glass plate 210 located on the
interior side of the windshield 20 is favorably greater than or
equal to 0.3 mm and less than or equal to 2.3 mm. The plate
thickness of the glass plate 210 being greater than or equal to 0.3
mm brings a satisfactory handling capability, and being less than
or equal to 2.3 mm prevents the mass of the windshield 20 from
becoming too heavy. However, the plate thickness of the glass plate
210 does not necessarily need to be uniform, and the plate
thickness may vary depending on the location as needed. Note that
in the case where the glass plate 210 located on the interior side
of the windshield 20 has a wedge shape in cross section, it is
favorable that the plate thickness at the thinnest part falls
within the range described above.
[0040] The plate thickness of the glass plate 210 is more favorably
greater than or equal to 0.5 mm and less than or equal to 2.1 mm,
and even more favorably greater than or equal to 0.7 mm and less
than or equal to 1.9 mm. Also, in order to efficiently transmit
heat from the heat generator 250 to the outer surface 22, it is
better that the thickness of the glass plate 210 is thin so as not
to necessitate heat excessively in heating, and the plate thickness
of the glass plate 210 is favorably less than or equal to 1.9 mm,
and more favorably less than or equal to 1.7 mm.
[0041] In the case where the windshield 20 has a curved shape, the
glass plates 210 and 220 are applied with bending-forming after
shaping by the float process and before bonding with the interlayer
230. The bending-forming is performed by softening the glass by
heating. The heating temperature of the glass during the
bending-forming is approximately 550.degree. C. to 700.degree.
C.
[0042] Returning to the description in FIG. 2, as the interlayer
230 to bond the glass plate 210 and the glass plate 220 together,
thermoplastic resin is often used; for example, plastic polyvinyl
acetal resin, plastic polyvinyl chloride resin, saturated polyester
resin, plastic saturated polyester resin, polyurethane resin,
plastic polyurethane resin, ethylene acetic acid vinyl copolymer
resin, ethylene ethyl acrylate copolymer resin, and the like may be
listed, which are thermoplastic resin conventionally used for this
kind of application.
[0043] Among these, plastic polyvinyl acetal resin is suitably used
because it has a superior balance of properties including
transparency, weather resistance, strength, adhesive strength,
penetration tolerance, impact energy absorption, moisture
resistance, heat insulation, and sound insulation. One of these
thermoplastic resins may be used singly, or two or more may be used
together. The word "plastic" as in the above "plastic polyvinyl
acetal resin" means that it is plasticized by adding a plasticizer.
The same applies to other plastic resins.
[0044] As the polyvinyl acetal resin described above, polyvinyl
formal resin obtained by having polyvinyl alcohol (may be referred
to as "PVA" below as necessary) react with formaldehyde; polyvinyl
acetal resin in a narrow sense obtained by having PVA react with
acetaldehyde; polyvinyl butyral resin (may be referred to as "PVB"
below as necessary) obtained by having PVA react with
n-butyraldehyde; and the like may be listed. Among these, in
particular, PVB is suitably used because of its superior balance of
properties including transparency, weather resistance, strength,
adhesive strength, penetration tolerance, impact energy absorption,
moisture resistance, heat insulation, and sound insulation. Note
that these polyvinyl acetal resins may be used singly, or two or
more may be used together. However, the material for forming the
interlayer 230 is not limited to the thermoplastic resin.
[0045] The layer thickness of the interlayer 230 is favorably
greater than or equal to 0.5 mm at the thinnest part, and more
favorably greater than or equal to 0.6 mm. The layer thickness of
the interlayer 230 being greater than or equal to the lower limit
provides a sufficient penetration resistance required as a
windshield. Also, the layer thickness of the interlayer 230 is less
than or equal to 1 mm at the thickest part. In the case where the
maximum value of the layer thickness of the interlayer 230 is less
than or equal to 1 mm, the thermal conduction from the heat
generator 250 does not become too small due to the presence of the
interlayer 230. Also, the maximum value of the layer thickness of
the interlayer 230 being less than or equal to 1 mm enables to
prevent the mass of the laminated glass from becoming too heavy.
The maximum value of the layer thickness of the interlayer 230 is
more favorably less than or equal to 0.95 mm, and even more
favorably less than or equal to 0.9 mm.
[0046] Note that the interlayer 230 may have three or more layers.
For example, by forming the interlayer 230 with three layers and
setting the hardness of the middle layer to be lower than the
hardness of both of the side layers by adjusting a plasticizer or
the like, the sound insulation performance of the laminated glass
can be improved. In this case, the hardness of the side layers may
be the same or may differ. Here, the hardness of layers of the
interlayer 230 can be measured as the Shore hardness. In the case
where the interlayer 230 is a sound insulation performance
improving film having multiple layers, a phenomenon that
thermoplastic resin is melted and deformed by the heat of the heat
generator to appear as distortion may tend to occur. In the present
invention, it is not necessary to make the layer thickness of the
interlayer having lower thermal conductivity unnecessarily thick;
therefore, the heat generator does not need to generate an
excessive heat generation amount, and thereby, even in the case of
the interlayer 230 being a sound insulation performance improving
film, the occurrence of distortion can be controlled.
[0047] Normally, the light source of an HUD is located in the lower
part in the vehicle interior, from which light is projected toward
the laminated glass. A projected image is reflected on the back and
front surfaces of the glass plates 210 and 220; therefore, in order
to superimpose the two reflected images on each other so as to
avoid generation of double images, the plate thickness of the glass
plate needs to change in parallel with the projection direction. In
the case where the plate thickness of the glass plate 220 changes
in a direction perpendicular to the streaks, in order to be used as
a glass on which information is projected, the glass must be used
in a direction where the streak direction is perpendicular to the
projection direction; that is, streaks are parallel to the line of
sight of an observer (driver) in the vehicle interior, and the
visibility is deteriorated by perspective distortion.
[0048] In order to improve the visibility, it is favorable that a
laminated glass manufactured using the glass plate 210, the glass
plate 220, and the interlayer 230 is arranged such that streaks of
the glass plate 210 and streaks of the glass plate 220 formed by a
float process are perpendicular to each other. This arrangement
alleviates distortion that would be worsened by using the glass
plate 210 alone, by the presence of the glass plate 220 where the
streaks are perpendicular to each other, and of the interlayer 230
that bonds the glass plate 210 with the glass plate 220.
[0049] In order to produce an interlayer 230, for example, a resin
material to form the interlayer 230 is appropriately selected from
among those described above, to which extrusion molding is applied
in a heated and molten state by using an extruder. The extrusion
conditions such as the extrusion rate of the extruder are set to be
uniform. After that, in order to give curvature to the upper side
and the lower side according to the design of the windshield 20,
for example, the resin layer to which the extrusion molding has
been applied is extended as necessary, to complete the interlayer
230.
[0050] To manufacture a laminated glass, a laminate is formed by
sandwiching the interlayer 230 and the heat generator 250 between a
glass plate 210 and a glass plate 220, and then, for example, this
laminate is placed in a rubber bag to be bonded in a vacuum of -65
to -100 kPa at a temperature of approximately 70 to 110.degree.
C.
[0051] Further, applying a press-bonding treatment of heating and
pressing to the laminate under conditions of, for example, 100 to
150.degree. C. and a pressure of 0.6 to 1.3 MPa, a laminated glass
having more excellent durability can be obtained. However, in some
cases, this heating and pressing process may not be used to
simplify the process and in consideration of the characteristics of
the materials put into the laminated glass.
[0052] Note that other than the interlayer 230, a film or device
having a function such as infrared reflection, light emission,
power generation, light control, visible light reflection,
scattering, decoration, absorption, or the like may be provided
between the glass plate 210 and the glass plate 220.
[0053] FIG. 3 is a partial cross-sectional view illustrating a
windshield according to a comparative example, viewed in the same
direction as in FIG. 2. As illustrated in the comparative example
in FIG. 3, in the windshield that is HUD-compatible, a structure in
which the interlayer 230 has a wedge shape in cross section and the
plate thicknesses of the glass plates 210 and 220 are uniform is
not favorable for the following reasons.
[0054] That is, the interlayer 230 has a lower thermal conductivity
than the glass plate 210 and the glass plate 220. For example, in
the case of the interlayer 230 being polyvinyl butyral resin (PVB),
the thermal conductivity at room temperature is approximately 0.19
to 0.21 W/mK, and in the case of ethylene-vinyl acetate copolymer
resin (EVA), the thermal conductivity at room temperature is
approximately 0.17 W/mK. It is favorable that the interlayer 230
used in the present invention is PVB having a relatively high
thermal conductivity.
[0055] Note that, in contrast, in the case of the glass plates 210
and 220 being soda-lime glass, aluminosilicate, organic glass, or
the like, the thermal conductivity at room temperature is
approximately 0.3 to 1.3 W/mK. Among these, soda-lime glass having
a relatively high thermal conductivity of 1.0 W/mK is
favorable.
[0056] Therefore, in the structure illustrated in FIG. 3, in the
upper side part where the interlayer 230 is thicker, the distance
over which heat is transmitted through the interlayer 230 having
low thermal conductivity is longer; therefore, the heat cannot be
transmitted efficiently toward the outer surface 22 side (the
outside of the vehicle) of the windshield 20. Therefore, the
function of defrosting (thawing) frozen water stuck on the outer
surface 22 of the windshield 20, or clearing off (defogging)
cloudiness of the outer surface 22 of the windshield 20 may not be
fully exhibited.
[0057] In contrast, as in the structure illustrated in FIG. 2, when
the glass plate 220 having a thermal conductivity higher than the
interlayer 230 has a wedge shape in cross section, the layer
thickness of the interlayer 230 having a lower thermal conductivity
is not thicker, whereas the glass plate having the higher thermal
conductivity is thicker; therefore, heat from the heat generator
250 can be efficiently transmitted to the outside of the vehicle.
As a result, while controlling the HUD double images and
maintaining the effect of sufficiently reducing transmitted double
images, the function of defrosting (thawing) frozen water stuck on
the outer surface 22 of the windshield 20, or clearing off
(defogging) cloudiness of the outer surface 22 of the windshield 20
can be fully exhibited.
[0058] Note that although an example is illustrated in FIG. 2 in
which the glass plate 220 on the exterior side of the vehicle has a
wedge shape in cross section, as illustrated in FIG. 4, the glass
plate 210 on the interior side of the vehicle may have a wedge
shape. In this case, the heat transfer distance from the heat
generator 250 to the outside of the vehicle can be shortened, and
the influence caused by forming the glass plate 210 to have a wedge
shape in cross section can be eliminated.
[0059] The structures illustrated in FIGS. 2 and 4 are particularly
effective in the case where the thermal conductivity of the
interlayer 230 at room temperature is less than or equal to 0.3
W/mK. Also, this is particularly effective in the case where the
heat generation amount per unit area of the heat generator 250 is
greater than or equal to 400 W/m.sup.2 and less than or equal to
1200 W/m.sup.2. In the case where the heat generation amount is
less than or equal to 1200 W/m.sup.2, the temperature of the
windshield does not become too high. In the case where the heat
generation amount is greater than or equal to 400 W/m.sup.2, a
sufficient heating effect can be obtained for the windshield.
[0060] Also, the ratio of the plate thickness of a glass plate
having a wedge shape in cross section (the glass plate 220 in FIG.
2 or the glass plate 210 in FIG. 4) to the layer thickness of the
interlayer 230 at a corresponding position (the plate thickness of
the glass plate/the layer thickness of the interlayer) is favorably
greater than or equal to 0.7 and less than or equal to 5.0 from the
viewpoint of maintaining a good thermal conduction, and also from
the viewpoints of the mass and the penetration resistance as a
laminated glass. The value of the ratio of the plate thickness of
the glass plate to the layer thickness of the interlayer is more
favorably greater than or equal to 2.0 and less than or equal to
4.5.
[0061] The present invention is also effective particularly in a
laminated glass for vehicles having an information
transmission/reception area in the upper-side peripheral part as
illustrated in FIG. 1. The configuration of the present invention
enables the heat generator to efficiently clear off frost and the
like stuck on the information transmission/reception area of the
laminated glass; therefore, devices corresponding with ADAS
(Advanced driver-assistance systems) arranged in the vehicle on the
interior side of the laminated glass, such as cameras and sensors,
operate normally. In particular, in the upper-side peripheral part,
as the thickness of the HUD-compatible laminated glass increases,
the present application is even more useful.
EXAMPLES
[0062] A pair of two glass plates having a windshield shape, a
height of 1180 mm, and a width of 1480 mm were prepared. Then,
tungsten wires having a current-flowing mechanism were arranged
between an interlayer and the glass plate on the interior side of a
vehicle, to which pressure bonding (preliminary pressure bonding
under reduced pressure and main pressure bonding in an autoclave)
is applied to produce a laminated glass. In the following, the
glass plate on the interior side of the vehicle will be referred to
as the inner plate, and the glass plate on the exterior side of the
vehicle will be referred to as the outer plate.
[0063] Note that the physical properties of the prepared glass
plates and the interlayer were as shown in FIG. 5, and the
configurations of produced laminated glasses were as illustrated in
Examples 1 to 6 and Comparative Examples 1 to 3 in FIG. 6. Note
that in FIG. 6, for example, "2" indicates that the thickness is 2
mm and is uniform, and for example, "2+WEDGE SHAPE" indicates that
the thickness on the lower side is 2 mm and has a wedge shape in
cross section. In these Examples and Comparative Examples,
soda-lime glass (product name FL: manufactured by AGC Inc.) was
used for the glass plates, and PVB (product name QZH1: manufactured
by Eastman Chemical Company) was used for the interlayer.
[0064] As illustrated in FIG. 6, in Examples 1 to 6 , the inner
plate (on the interior side of the vehicle) or the outer plate (on
the exterior side of the vehicle) was formed to have a wedge shape
in cross section, and the interlayer was formed to have a uniform
layer thickness. Also, in Comparative Examples 1 to 3, the
interlayer had a wedge shape in cross section, and both the inner
plate and the outer plate had uniform plate thicknesses. Also, the
laminated glasses of Examples 1 to 6 and Comparative Examples 1 to
3 illustrated in FIG. 6 were adjusted to have a heat generation
amount of 1000 W/m.sup.2 by changing the thickness of the tungsten
wires and the applied voltage.
[0065] Then, the laminated glasses of Examples 1 to 6 and
Comparative Examples 1 to 3 were left in an environment at
-20.degree. C. for a sufficient period of time, and confirmed that
the actual temperature of the glass had reached -20.degree. C., and
put in a state of having frost on the front surface of the outer
plate.
[0066] Next, in this state, the laminated glasses of Examples 1 to
6 and Comparative Examples 1 to 3 were evaluated. Specifically, for
each of the laminated glasses, heat was generated by the heat
generation amount of 1000 W/m.sup.2, and the time to clear off the
frost at the location where the distance from the lower side was
1000 mm, namely, at the location where the thickness of the
laminated glass was thick, was measured. Also, for each of the
laminated glasses, the surface temperature of the glass plate on
the exterior side of the vehicle at the position where the distance
from the lower side was 1000 mm was measured when having
transitioned to a steady state.
[0067] From Examples 1 and 2 and Comparative Example 1 in FIG. 6,
in the case where the inner plate or the outer plate was formed to
have a wedge shape in cross section with a wedge angle of 0.6 mrad
(Examples 1 and 2), it was confirmed that the time to clear off the
frost at the measurement point was shorter and the surface
temperature of the outer plate in the steady state was higher than
in the case (Comparative Example 1) in which the interlayer was
formed to have a wedge shape in cross section with the wedge angle
of 0.6 mrad.
[0068] Also, from Examples 3 and 4 and Comparative Example 2 in
FIG. 6, in the case where the inner plate or the outer plate was
formed to have a wedge shape in cross section with a wedge angle of
0.3 mrad (Examples 3 and 4), it was confirmed that the time to
clear off the frost at the measurement point was shorter and the
surface temperature of the outer plate in the steady state was
higher than in the case (Comparative Example 2) in which the
interlayer was formed to have a wedge shape in cross section with
the wedge angle of 0.3 mrad.
[0069] Also, from Examples 5 and 6 and Comparative Example 3 in
FIG. 6, in the case where the inner plate or the outer plate was
formed to have a wedge shape in cross section with a wedge angle of
0.6 mrad (Examples 5 and 6), it was confirmed that the time to
clear off the frost at the measurement point was shorter and the
surface temperature of the outer plate in the steady state was
higher than in the case (Comparative Example 3) in which the
interlayer was formed to have a wedge shape in cross section with
the wedge angle of 0.6 mrad.
[0070] Also, from Examples 1 and 2 and Examples 3 and 4 in FIG. 6,
it could be understood that a greater wedge angle brought a more
remarkable effect of forming the inner plate or the outer plate to
have a wedge shape in cross section.
[0071] Also, from Examples 1 and 2 and Examples 5 and 6 in FIG. 6,
a thinner plate thickness at the thinnest part of the inner plate
brought a more remarkable effect of efficiently transmitting the
heat from the tungsten wires to the outside of the vehicle. This is
because a thinner inner plate makes the specific heat of the glass
smaller, and the heat that would be used for increasing the
temperature of the inner plate can be distributed to the other
part.
[0072] Also, from Examples 1 to 6 in FIG. 6, the cases where the
inner plate was formed to have a wedge shape in cross section
showed more remarkable effects of efficiently transmitting the heat
from the tungsten wires to the outside of the vehicle.
[0073] In this way, in the laminated glasses, it was confirmed that
the heat from the tungsten wires as the heat generator could be
efficiently transmitted to the outside of the vehicle by forming
the inner plate or the outer plate, which had a higher thermal
conductivity than the interlayer, to have a wedge shape in cross
section.
[0074] Also, each of the laminated glasses in Examples had a wedge
shape in cross section having a predetermined wedge angle in the
HUD display area; therefore, no HUD double image was generated, and
the HUD quality was good.
[0075] As above, the preferred embodiments and the like have been
described in detail. Note that various modifications and
substitutions can be made to the above-described embodiments and
the like, without deviating from the scope described in the
claims.
* * * * *